CVE-2026-27026 MEDIUM

CVE-2026-27026: pypdf possibly has long runtimes for malformed FlateDecode streams

Vendor Py-Pdf
Product pypdf
Weakness CWE-770 · Uncontrolled resource consumption
Published February 20, 2026
Last update February 24, 2026
View on NVD All CVEs

CVSS base score

6.9/10
Attack vector Local
Attack complexity Low
Privileges required None
User interaction None
Confidentiality —
Integrity —

CVSS vector

CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

What the vulnerability does

01Description

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.1, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires a malformed /FlateDecode stream, where the byte-by-byte decompression is used. This vulnerability is fixed in 6.7.1.

Key dates

02Disclosure timeline

February 20, 2026 CVE published
February 24, 2026 Record updated